Download Supplemental Information Dietary Reference Intakes, continued

Carbohydrates
S ESSI ON 2 : DI E TA RY F I BE R
DR A ZA DE H N A DJA R ZADEH
A ZA DE HNA JA RZADEH@GM AIL .COM
Session Overview for Instructor
Key Messages
Adequate amounts of dietary fiber help to maintain
health and reduce risks of colon cancer and coronary
artery disease
Sources of dietary fiber in the food supply are:
Grain products
Vegetables
Fruits
Legumes, nuts, and soy
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Fiber
Fiber is the structural part of plants and is found in vegetables, fruits,
grains and legumes.
Most dietary fibers are polysaccharides, like starch, but they are not
digestible.
The human body lacks the enzymes needed to digest and absorb fiber.
As a result fibers reach the lower intestine intact where intestinal bacteria
can ferment some fiber.
Fiber
Fiber
Nonstarch polysaccharide fibers
◦
◦
◦
◦
◦
Cellulose
Hemicellulose
Pectin
Gums
Mucilages
Nonpolysaccharide fiber
◦ Lignins
◦ Cutins
◦ Tannins
Resistant Starches
Types of Fiber
There are many different types of fiber, in general fibers can be divided into
two types based on their physical properties.
◦ Soluble fibers
◦ Insoluble fibers
Soluble Fibers
Soluble fibers dissolve in water, form gels and are easily digested by bacteria
in the lower intestine.
◦ Provides a feeling of fullness.
◦ Slow down the rate food leaves the stomach.
◦ May have a role with heart disease, diabetes and colon cancer
Found in legumes and fruits
Insoluble Fiber
Insoluble fibers absorb water and swell up resulting in a larger softer stool
that is easier and quicker to pass.
◦ Provides a feeling of fullness
◦ Helps with intestinal function
◦ May help with colon cancer
Found in grains and vegetables
Fiber and Health
Both fiber types are important for health.
Fibers are beneficial for many conditions; constipation, diarrhea, diverticular
disease, heart disease, diabetes and colon cancer.
Fiber is only one factor involved in these conditions.
Fiber and Health
Foods high fiber have many factors that may be factors in lowering disease
risk.
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◦
◦
◦
◦
High fiber
Low in fat
High vitamins (antioxidants)
High in minerals
High in phytochemicals
Intestinal Function
Insoluble fibers absorb water resulting in a larger, softer stool that is faster
and easier to eliminate, which can help with:
◦ Constipation
◦ Hemorrhoids
◦ Diverticular disease
Colon Cancer
Both insoluble and soluble fibers may protect against colon cancer
◦ Insoluble fibers absorb water making a larger, softer stool which can:
◦ Dilute potential carcinogens
◦ Reduce transit time so the colon is exposed to any cancer causing substance for less time.
◦ Soluble fibers can bind bile acids, potential carcinogens, and increase their
excretion.
Heart Disease
As mentioned, soluble fibers can bind to bile acids and increase their
excretion.
With fewer bile acids in the intestine, less fat is absorbed.
Also by increasing bile acid excretion, the liver must use its cholesterol to
make new bile acids.
Diabetes
Soluble fibers may have a favorable effect on blood glucose.
Soluble fibers decrease the rate at which food is released from the
stomach and delays glucose absorption into the blood.
This may help prevent wide swings in blood glucose throughout the day.
Weight Management
Foods rich in complex carbohydrates tend to be low in fat and added
sugars which can help with weight management by providing fewer
calories.
In addition, as fibers absorb water they swell up creating a feeling of
fullness and delaying hunger.
How Much Fiber
The National Research Council set a Dietary Reference Intake (DRI) for dietary
fiber.
An adequate Intake (AI) for dietary fiber was set at 14 grams dietary fiber per
1,000 calories.
◦ Thus for a reference 2,000 calorie diet recommended intake would be 28 grams
per day.
Too Much Fiber
Dietary fiber can bind some minerals and decrease their absorption.
However, if mineral intake is adequate a recommended dietary fiber intake
will not compromise mineral balance.
Fiber intake is like all nutrients - “more” is not always “better.” Consuming
a diet that provides a variety of nutrients is the key.
Food Sources of Fiber
Foods are the best source of fiber, get both soluble and insoluble fiber.
Food sources of fiber include fruits, vegetables, whole grain products,
legumes, nuts and seeds.
Cooking processing and removing peels can lower fiber content.
Tips for Increasing Fiber
Increase fiber slowly. Increasing fiber too fast may cause bloating and gas.
Since some fiber absorbs water it also is important to drink plenty of fluids
when increasing dietary fiber.
Tips for Increasing Fiber
Because fibers absorb liquids drink plenty of fluids when increasing fiber.
As with all nutrients, “more” is not “better.” Moderation is the key.
Summary of Dietary Fiber Classes
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SLIDE 21
Other Sweeteners
Nutritive sweeteners
◦ Sugar alcohols (sorbitol, mannitol, xylitol)
Nonnutritive sweeteners
◦ Artificial sweeteners in food
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SLIDE 22
Sweetness of Sugars and Artificial
Sweeteners
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SLIDE 23
Energy Function of Carbohydrates
Basic fuel supply
◦ Energy for physical activities and all work of body cells
Reserve fuel supply
◦ Provided by glycogen
◦ Maintains normal blood glucose level
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SLIDE 24
Special Tissue Functions of
Carbohydrates
Liver
◦ Glycogen reserves protect cells from depressed metabolic function
Protein and fat
◦ Carbohydrates regulate proteins and fat
(Cont'd…)
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SLIDE 25
Special Tissue Functions of
Carbohydrates
(…Cont’d)
Heart
◦ Glycogen is vital emergency fuel for heart muscle
Central nervous system
◦ Brain dependent on minute-to-minute supply of glucose
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SLIDE 26
Food Sources of Carbohydrates
Starches
◦ Provide fundamental complex carbohydrates
Sugars
◦ High-sugar diets carry health risks
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SLIDE 27
Carbohydrate Content of Foods
(Cont'd…)
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SLIDE 28
Carbohydrate Content of Foods
(…Cont’d)
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SLIDE 29
Digestion of Carbohydrates
Mouth
◦ Mechanical or muscle functions break food mass into smaller particles
Stomach
◦ Peristalsis continues mechanical digestive process
(Cont'd…)
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SLIDE 30
Digestion of Carbohydrates
(…Cont’d)
Small intestine
◦ Peristalsis continues mechanical digestions
◦ Pancreatic secretions
◦ Intestinal secretions
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SLIDE 31
Summary of Carbohydrate Digestion
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SLIDE 32
Body Needs for Carbohydrates
Dietary Reference Intakes
◦ 45%-65% of adult’s total caloric intake should come from carbohydrate foods
◦ Limit sugar to no more than 25% of calories consumed
Dietary Guidelines for Americans
◦ Does not outline specifics for caloric consumption or where kilocalories should come from
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Mosby, Inc.
SLIDE 33
Daily Recommendations of Dietary Fiber
Needed* by Age/Gender
Children
Males
Females
Years
Grams
Years
Grams
Years
Grams
1-3
19
9-13
31
9-18
26
4-8
25
14-50
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19-50
25
51+
30
51+
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*Recommendations, in grams, are based on
Estimated Average Requirements (EARs).
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Supplemental Information
Background Information on the
Dietary Reference Intakes
The Institute of Medicine of the National Academy of Sciences
publishes the Dietary Reference Intakes (DRI) for dietary
components, including macronutrients, vitamins, minerals, and
fiber. The DRIs consist of the RDAs, EARs, AIs, and ULs.
Recommended values are provided for each life cycle group—
from birth through childhood, sexual maturity, midlife, and old
age.
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Supplemental Information
Dietary Reference Intakes, continued
Nutrient Values Provided by the
Dietary Reference Intakes
Recommended Dietary
Allowance (RDA)
The average daily intake level
sufficient to meet the nutrient
requirements of 97 to 98
percent of healthy individuals.

Tolerable Upper Level (UL)
The highest level of daily
nutrient intake that is likely to
pose no risks of adverse
health effects to almost all
individuals in the general
population.
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Supplemental Information
Dietary Reference Intakes, continued

Estimated Average
Requirement (EAR)
The
nutrient intake value sufficient
to meet the requirements of
half the healthy individuals in
a group. The Nutrient
Content of the U.S. Food
Supply Series uses this DRI
for nutrient comparisons.
Adequate Intake (AI)
The recommended daily
intake based on
approximations of nutrient
intake by a group (or groups)
of healthy people. It is used
when the RDA cannot be
determined.
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